As for how subs avoid torpedoes, that is VERY sensitive topic, nobody will tell you. Anyway sub at flank should turn quite well (better then how in DW). Ramius simply had to know what he must do against Russian torpedoes.
In DW torpedo avoidance means don't get shot at at the first place. Don't be there when the torpedo is there comes next. CMs and wild turns comes next, in that case you must place CM so torpedo finds it right in it's way and closer then you .. but when it flies past CM you must not be there anymore. Quite tricky without knowing exactly where the torpedo is. Try to stick to points one and two.
I can't compare to SC, I did not play it. In DW AI is quite simple. Seek, investigate, kill. With LWAMI it shoots back. I say simple, but that does not mean easy to beat. But the balance is job if mission designer here.